Mechanical ventilatory support is widely accepted as an effective form of therapy and means for treating patients with respiratory failure. The early generation of mechanical ventilators, prior to the mid-1960s, were designed to support alveolar ventilation and to provide supplemental oxygen for those patients who were unable to breathe on their own. Since that time, mechanical ventilators have become more sophisticated and complicated in response to increasing understanding of lung pathophysiology. For example, CPAP (Continuous Positive Airway Pressure), BiPAP (Bilevel Positive Airway Pressure) and SIMV (Synchronized Intermittent Mandatory Ventilation) are effective in preventing need for intubation and also decreasing mortality in patients with acute respiratory failure.
Even though the ventilator technology is constantly improving, ventilator dependence is still a serious medical and economic problem. It is well known that severe and sometimes lethal complications may develop the longer a patient is on ventilator support. In addition, as ventilator therapy is provided in specialized and very expensive Intensive Care Unit environments, there is a need to minimize ventilator dependency. Weaning the patients from artificial ventilation is among the most difficult challenges of the regarding intensive care ventilation.
Prior art ventilator weaning monitoring methods are not efficient enough and are often depending on subjective impressions of clinical fatigue or distress and/or arterial blood gas derangements that of necessity measure failure after the failure has already developed. More modem monitoring techniques such as the ratio of Tidal Volume to Respiratory Rate are still relatively crude indices of weaning performance. Weaning from ventilator dependency is potentially hazardous due to unexpected precipitous ventilatory failure, and early warning by appropriate monitoring means is imperative for patient safety. Further, controlled stress of weakened respiratory muscles is imperative in order to recondition these muscles, but in addition to not over-stress these recovering muscles and therefore cause further damage. It is often difficult to safely define the proper degree of weaning stress clinically.
There is thus a need in the art for systems, devices and methods that would allow monitoring the constantly changing condition of a patient undergoing weaning from ventilation.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.